Radio frequency lateral double diffused field effect transistor and its manufacturing method

Abstract

The invention discloses a radio frequency lateral double-diffusion field effect transistor, which comprises a polysilicon gate and a Faraday shielding layer, and the Faraday shielding layer is a polysilicon Faraday shielding layer. The RF lateral double-diffusion field-effect transistor of the present invention adopts the structure of the polysilicon Faraday shielding layer. Compared with the traditional preparation process of the Faraday shielding layer, the preparation process is simple, and only one thermal oxidation process is added, and the oxide layer under the Faraday shielding layer is reduced once. Deposition and metal deposition and etching process, the quality of the oxide layer under the Faraday shielding layer prepared by this method is better than that of the ordinary Faraday shielding layer grown by deposition, thereby enhancing the durability of the device; and this Compared with common metal Faraday shielding layer devices, the invented device has the same breakdown voltage, on-resistance and other characteristics. At the same time, the stepped gate structure prepared by this method can also play a role in suppressing hot carrier injection (HCI).

Description

technical field [0001] The invention relates to a semiconductor integrated circuit, in particular to a radio frequency lateral double-diffusion field effect transistor, and also relates to a manufacturing method of the transistor. Background technique [0002] With the advent of the 3G era, more and more communication fields require the development of more powerful radio frequency (RF) devices. Radio Frequency Lateral Double Diffused Field Effect Transistor (RFLDMOS), due to its very high output power, has been widely used in portable wireless base station power amplification as early as the 1990s, and its application frequency is 900MHz-3.8GHz. Compared with traditional silicon-based bipolar transistors, RFLDMOS has better linearity, higher power and gain. Today, RFLDMOS is more popular than bipolar, and GaAs devices. [0003] The current structure of RFLDMOS is as follows figure 1 As shown, a substrate doped with a high-concentration P-type impurity, that is, a P-type s...

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Problems solved by technology

[0004] At present, under normal circumstances, the oxide layer under the Faraday shielding layer prepared by this method is grown by deposition, and its quality is generally poor, and its quality can directly affect the evaluation of the reliability of the device.

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